A contract manufacturer ("CM") is a firm that manufactures components or products for another "hiring" firm. Many industries utilize this process, especially the aerospace, defense, computer, semiconductor, energy, medical, personal care, and automotive fields. Some types of contract manufacturing include CNC machining, complex assembly, aluminum die casting, grinding, broaching, gears, and forging and complex electronic packaging, manufacturing and assembly.

In a contract manufacturing business model, the hiring firm - typically an OEM - approaches the contract manufacturer with a design or formula. The contract manufacturer will quote the parts based on processes, labor, tooling, and material costs. Typically an OEM will request quotes from multiple Contract Manufacturers. After the bidding process is complete, the hiring firm will select a source, and then, for the agreed-upon price, the Contract Manufacturer acts as the hiring firm's factory, producing and shipping units of the design on behalf of the hiring firm.

Many well-known companies use contract manufacturing as an alternative to operating and maintaining their own factories. Contract manufacturing can be used for anything from single components to a complete product. Printers, computers, cellular phones, and personal care products are all examples of products that are made using this method.

In an international context, establishing a foreign subsidiary as a Contract Manufacturer can have favorable tax benefits for the parent company, allowing them to reduce overall tax liabilities and increase profits, depending upon the activities of the Contract manufacturer.